1. Here, we found that MFC is not calling getMessage () to take a message from the thread message queue, but call PeekMessage (). The reason is that getMessage () is a function with synchronous behavior. If there is no message in the message queue, getMessage () will always block, so that the thread is on the sleep state until there is one or more messages in the message queue, the operating system will Wake up this thread, getMessage () will return. If the thread is in sleep, it will not make the thread with the so-called "idle" state of the MFC; and PeekMessage () is a function with asynchronous behavior if the message queue is No message, it will return to 0 immediately, which will not cause the thread to sleep.
